The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a functional block diagram of a hard disk drive (HDD) 100 is presented. The HDD 100 includes a hard disk assembly (HDA) 101 and an HDD printed circuit board (PCB) 102. The HDA 101 may include a magnetic medium 103, such as one or more platters that store data, and a read/write device 104. The read/write device 104 may be arranged on an actuator arm 105 and may read and write data on the magnetic medium 103.
Additionally, the HDA 101 includes a spindle motor 106 that rotates the magnetic medium 103 and a voice-coil motor (VCM) 107 that actuates the actuator arm 105. The VCM 107 may control the height of the read/write device 104 above the magnetic medium 103. This is referred to as flyheight control, and may use a constant power single-ended signal. A preamplifying device 108 amplifies signals generated by the read/write device 104 during read operations and provides signals to the read/write device 104 during write operations.
The preamplifying device 108 provides bias power to the read/write device 104. The read/write device 104 may include a magnetoresistive (MR) head, which may be a giant MR head. The preamplifying device 108 may bias the MR head with a differential signal having minimal common mode voltage. To maintain a uniform bias, the differential signal may deliver a constant power to the MR head.
The HDD PCB 102 includes a read/write channel module (hereinafter, “read channel”) 109, a hard disk controller (HDC) module 110, a buffer 111, nonvolatile memory 112, a processor 113, and a spindle/VCM driver module 114. The read channel 109 processes data received from and transmitted to the preamplifying device 108. The HDC module 110 controls components of the HDA 101 and communicates with an external device (not shown) via an I/O interface 115. The external device may include a computer, a multimedia device, a mobile computing device, etc. The I/O interface 115 may include wireline and/or wireless communication links.
The HDC module 110 may receive data from the HDA 101, the read channel 109, the buffer 111, nonvolatile memory 112, the processor 113, the spindle/VCM driver module 114, and/or the I/O interface 115. The processor 113 may process the data, including encoding, decoding, filtering, and/or formatting. The processed data may be output to the HDA 101, the read channel 109, the buffer 111, nonvolatile memory 112, the processor 113, the spindle/VCM driver module 114, and/or the I/O interface 115.
The HDC module 110 may use the buffer 111 and/or nonvolatile memory 112 to store data related to the control and operation of the HDD 100. The buffer 111 may include DRAM, SDRAM, etc. Nonvolatile memory 112 may include any suitable type of semiconductor or solid-state memory, such as flash memory (including NAND and NOR flash memory), phase change memory, magnetic RAM, and multi-state memory, in which each memory cell has more than two states. The spindle/VCM driver module 114 controls the spindle motor 106 and the VCM 107. The spindle/VCM driver module 114 may provide a constant power single-ended signal to the VCM 107 for consistent flyheight control. The HDD PCB 102 includes a power supply 116 that provides power to the components of the HDD 100.